1. Field of the Invention
This invention relates to a photogrammetric analytical measurement system, in which a survey map is produced on the basis of a set of photographed pictures obtained at two different photographing positions.
2. Description of the Related Art
For example, photogrammetry is carried out at a traffic accident spot. The traffic accident spot is photographed by a camera from at least two different positions, and a survey map of the traffic accident spot is produced based on a set of photographed pictures obtained at the different positions.
In particular, a two-dimensional coordinate system is defined on each of the photographed pictures, and two-dimensional positions of the objects, which are recorded on each picture, are determined by the corresponding two-dimensional coordinate system. Then, a three-dimensional coordinate system is defined on the basis of the two sets of two-dimensional coordinate systems, and three-dimensional positions of the recorded objects are calculated with respect to the three-dimensional coordinate system on the basis of the two-dimensional positions of the recorded objects on the two-dimensional coordinate systems. Thus, it is possible to produce a survey map of the traffic accident spot by drawing the objects on a sheet of paper in such a manner that the objects are projected on one of the three planes defined by the three-dimensional system.
Before the three-dimensional positions of the recorded objects can be accurately determined, it is necessary to properly and precisely designate a set of conspicuous points, representing each object, on the photographed pictures with respect to the two-dimensional coordinate systems. Thus, for example, although a continuous line, such as a painted lane marking, is photographed, it is impossible to draw the continuous line on the survey map, because the continuous line has no conspicuous points.
Therefore, conventionally, when a continuous line, such as a painted lane marking, must be drawn on a survey map, markers are placed on and along the continuous line at suitable intervals. Of course, when plural continuous lines are drawn on the survey map, the placing of the markers must be carried out with respect to each of the plural continuous line.